Process of producing metal foil or leaf.



UNITED STATES PATENT OFFICE.

GEORG ALEFELD, OF DARMSTADT, GERMANY, ASSIGNOR TO THE PHARMA- ZEUTISCHES INSTITUT LUDVIG \VILHELM GANS, OF FRANKFORT-ON- THE-MAIN, GERMANY.

PROCESS'OF PRODUCING METAL FOIL OR LEAF.

SPECIFICATION forming part of Letters Patent N 0. 645,197, dated March 13, 1900.

Application filed February 21, 1899. Serial No. 706,361. (No specimens.) I

To all whom it may concern: 7

Be it known that I, GEORG ALEFELD, a citizen of Germany, residing at Darmstadt, in the- Empire of Germany, have invented a certain new and useful Improved Process forthe'Production of Metal Foil or Leaf; and I do hereby declare the following to be a full, clear, and.

exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention consists of a new process for the production of metal leaf, such as gold and silver leaf or that of the metals of the platinum group or of alloys or mixtures of the same. In this process the so-called lusters or lustrous preparations of the metals are used, which, now sold and used for the decoration of porcelain, glass, &c., are organic compounds of metals (resin-acid compounds or sulfureted resin compounds or products of the decomposition of metallic chlorids by heating them with lavender-oil) mixed in their application with an ethereal oil, such as lavender-oil. Such lusters are known of a great many metals; but there is a very remarkable difference between those which have for basis the so-called precious metals-t'. 6., gold, silver, and all the metals of the platinum group-and those which have for basis the common unnoble (non-precious) metals. The first ones when applied upon porcelain, glass, or metal and then burned in leave behind a thin skin of metal, while the lusters of the unnoble metals when treated in the same manner form a skin of metallic oxid.

My process is carried out as follows: I spread a solution of a ceramic luster-for example, the resin-acid compound of a metallic oxid mixed with an ethereal oil-upona smooth surface of a material which is acidresistant and capable of enduring unimpaired the temperature usually employed to burn in the ceramic luster employed-such as porcelain, for example. The ceramic luster is then burned in upon the porcelain or its substitute in the usual manner. Fluxes easily soluble in acids-such as borosilicates or phosphates of soda, &c.may be substituted for a ceramic luster in this step of my process, if treated in the same way, by laying them on a plate and burning them in. Upon this bed, as I shall call it, after it has been burned in, a ceramic lustrous preparation of the desired noble metal is laid while in the condition in which it is ordinarily applied in decorating porcelain, &c., and is then burned in in the usual manner. This may be repeated'again and again until the desired thickness is attained, if one coat is thought insufficient for the intended purpose, or it may be thickened by electrolytic deposition of the metal. Thus a skin, so to speak, of the desired noble metal is formed upon a bed of ceramic luster,

which latter is attached to the porcelain or other plate upon which it was originally burned in. v

Though known in the art, it may not be amiss to mention that while the lusters of the non-oxidizable noble metals may be burned in without precaution against oxidation the lusters of the oxidizable metals, such as osmium, should be burned in in a reductionfiame, or, better still, in a closed muffle in the presence of a red ucing or neutral gassuch as illuminating-gas, hydrogen, or carbonic acid.

The next step is to detach the skin of the noble metal. This is done by immersing the plate in a solvent (principally inorganic and strong organic acids) of the bed, (the ceramic luster,) which is thus dissolved away, leaving the skin of the noble metal free, so that it can readily be peeled off from the plate; but these skins of the noble metal, particularly if very thin, are easily torn. To avoid such accidents, it is advisable to brush over the skin of noble metal with some form of tough varnish, such as collodion or a gutta-percha solution, after firing and before endeavoring to detach the skin from the plate. This protecting coating can be dissolved away by any suitable solvent as soon as the metal skin is removed from the plate, or it may be allowed to remain indefinitely to protect the metal skin until its removal becomes desirable.

It is obvious that foil or leaf of any metal or alloy which may be used in the form of a luster to decorate glass or porcelain by burning in may be made by my process provided the precaution be taken to select as a bed that is, the first application to the platea luster or flux which'is soluble in a solvent which does not attack the metal or alloy which it is desired to produce. It is also obvious that metals may thus be produced in the foil' or leaf form which by reason of their infusibility and lack of ductility and malleability are not adapted to the art of the gold-beater and cannot be rolled, while if deposited electrolytically in metallic form from a cathode these metals have so little cohesion that they cannot be stripped off in the form of a foil or leaf andused on any other surface than upon that where they are originally deposited. Osmium is a case in point which cannot be produced in thin-sheet form by any method heretofore known for thereasonsalready given, but which can be as easily produced by my method as foil or leaf of any other metal. It is also obvious that by simply applying the lusters to the plate in the form of apattern or design instead of covering the whole surface of the plate the resultant metal will be in pattern or design instead of in'a uniform leaf or sheet.

In order that my process may be better understood, I give some examples.

Eaccmnplc ISheet or ZccfgoZcl.-A fiat piece of porcelain is painted with magnesium luster and burned in in' the ordinary way. Then upon this magnesium luster the lustrousgold ceramic preparation is laid and the whole is again fired. Then upon this, if it is desired to toughen the metal sheet to facilitate handling,a collodion varnish is applied. The plate, with its adherent material, is then immersed in warm diluted sulfuric acid, when after a few minutes the sheet-gold skin can easily be removed. The collodion can thereafter be dissolved'by a suitable solvent, or in many cases it can simply be burned off, or it may be left to protect and strengthen the metal. Silver, iridium, and rhodium foil or leaf can be produced in the same way.

Example II--Sheet-0sm'ium.-'A piece of sheet-platinum of about half a millimeter thickness is covered with thorium-oxid luster in the condition in which it is applied for ceramic decoration and burned in. Then upon this a lustrous osmium ceramic preparation is laid and the Whole is again fired. Then upon this a gutta-percha solution may be applied and the whole dipped in dilute hydrochloric acid, which dissolves the thorium-oxid-luster bed, when the osmium sheet or leaf may be removed and the gutta-percha dissolved oif.

Having thus described my invention, what I claim as new, and desire to patent, is-

l. The within-described process of producing metal foil or leaf, which consists first in covering a suitable plate with a substance that is soluble and adapted to be burned into the plate, and firing'the same upon the plate to form a bed; second in applying thereto a ceramic-luster preparation of the desired metal and again firing; third, subjecting the whole to the action of a solvent which will attack the bed but not the desired metal; and finally peeling off the desired sheet or leaf from the plate.

2. The within-described process of producing metal foil or leaf, which consists first in covering an acid and heat resisting plate with a ceramic luster of an ordinary (non-precious) metal and firing the same upon the plate to form a bed second in applying thereto a ceramic-luster preparation of the desired metal and again firing; third, subjecting the whole to the action of a solvent which will attack the bed but not the desired metal, and finally ceramic-luster preparation of the desired metal and again firing; third, covering the same with a tough varnish, such as collodion fourth, subjecting the whole to the action of a solventwhich will attack the bed but not the desired metal; and fifth, peeling OK the desired metal sheet or leaf from the plate.

4. As a new article of manufacture detached cohesive foil or leaf of those metals which from lack of ductility or malleability, or both, cannot be reduced to foil or leaf form by hammering or rolling.

5. As a newarticle of manufacture, detached cohesive foil or leaf of the metal osmium,substantially as hereinbefore specified.

In testimony whereof 'I have hereunto affixed my signature in presence of two witnesses.

GEORG ALEFELD.

Vitnesses:

RICHARD GUENTHER, JEAN GRUND.

too 

